1. Field of the Invention
Embodiments of the present invention generally relate to the field of semiconductor manufacturing, and more specifically to a system and method for improving the yield of integrated circuits containing memory.
2. Description of the Related Art
The successful manufacture of integrated circuits depends on maximizing the yield, which is the number of tested good parts that are derived from each wafer. The greater the yield, the lower the overall cost of the product. The die area of the integrated circuit has a direct correlation to the yield. As die area increases, fewer dies can be fit on each wafer. As is well-known, larger die areas are more prone to manufacturing defects as well.
Typically, complex integrated circuits are comprised of a plurality of functional units providing set functionality and performance levels. For example, there may be shader, texture and arithmetic units within a graphics processing unit all working together to provide graphics functionality. After the integrated circuit is fabricated, the device undergoes a series of tests where each functional unit is tested to ensure that the integrated circuit is fully functional. If any functional unit fails a test, the entire integrated circuit is classified as inoperable and is discarded.
In an effort to increase yield, some designers add one or more redundant functional units to the design. If a failed functional unit is found, the failed unit is disabled and is replaced with one of the redundant functional units. For example, in a design that requires three Random Access Memory (RAM) arrays, a fourth RAM array may be added as a spare to be used when one of the three required RAM arrays fails. The problem with this approach is that the redundant functional units consume significant die area. If the redundant unit is not required, then the die area occupied by the redundant functional unit is wasted, and the yield is increased at the cost of die area usage.
As the foregoing illustrates, what is needed in the art is a way to increase yield without significantly increasing die area.